Airfoil



AIRFOIL 4 Sheets-Shea?l 1 W. K. ROSE Filed Jan. 18, 1937 July 25, 1939.

ATTORNEYS W. K. ROSE July 25, 1939.

AIRFOIL 4 shets-sheet 2 Filed Jan. 18, 1957 ATTO: NEYS.

July 25, 1939. w ROSE 2,167,601

AIRFOIL FiledJan. 1S, 1937 4 Sheets-Sheet I5 1N VENTOR` MMU/77 K. ,QueBY WWW *QV-Q ATTORNEYS W. K. ROSE July 25, 1939.

AIRFOIL Filed Jan. 18, 1937 4 Sheets-Sheet 4 Mmm /4 @wm BY ELM/,7 X/Qr-QATToRNEYs.

Patentecl July 25, 1939 lUNITED STATES PATENT OFFICE 13 Claims.

This invention relates to airplanes and more particularly to airfoilsused in the construction thereof which airfoils are characterized by oneor more passageways extending therethrough from the lower surface to theupper surface thereof, sc formed and constructed as to increase the liftand decrease the dra-g of the wing.

The invention deals Imore particularly with an improvement in the formof the passageways generally described and broadly claimed in my U. S.Letters Patent No. 2,077,070, granted April 13, 1937, on my copendingapplication Ser. No. 110,145, filed November 1936, but retains theessential characteristics of the passageways. Briefly, in my said U. S.Letters Patent No. 2,077,-

070, the cross sections of the passageways diminish gradually from theinlet to the outlet thereof and the vanes or blades bounding anddefining the passageways are so mounted and placed and their cooperatingcurved -surfaces so formed that the mean cross-sectional line of thepassageways gradually flattens from inlet to o utlet with no appreciablestraight line passage for air through the passageways from inlet tooutlet. Whereit is desired to increase the lift and decrease the dragthe inlet ports on the'lower surface of the airfoil are forward of theoutlet ports on the upper surface thereof and the curvature is upwardrespecting the lower surface of the airfoil. When pressure air flowsthrough the said passageways it is subjected toa gradual change ofmomentum and a force is developed within the passageways themselveswhich influences the lift drag ratio of the airfoil. As the resultantforce vector is directed upwardly and forwardly and as the air isdischarged from the passageways in a rearward direction the lift isincreased and the drag decreased. In my said U. S. Letters Patent No.2,077,070, I have pointed out wherein the force developed in passagewaysso characterized is analogous to that developed in turbines. Forconvenience of nomenclature and to avoid descriptive detail of thespecification and in certain of the claims hereof, I will hereinafterrefer to pas? sageways constructed for operation as just set forth aspassageways of the turbine type. Such nomenclature, it is to beunderstood, is not intended to be limited to the precise form ofpassageways chosen-for illustration in said U. S.

Letters Patent. (nor to the precise form of passageways herein shown)but as d'efinitive of the passageways broadly described in the said U.S. Letters Patent and in this application. Broadly speaking, suchpassageways herein extendthrough the airfoil in a general spanwisedirection and are therefore designated in the claims as substantiallyspanwise.

In turbine passageways for airfoils as above set forth, in straight-awayight wherein low angles of attack are employed ranging fromsubstantially 0 to 10 and more particularly within the lower range ofthese angles of attack, the present invention seeks to reduce the dragbelow that heretofore possible. In accomplishing this I primarilymodifyvthe form of the inlet port 10 of the passageways so that theforward vane or blade projects downwardly beneath the rearward vane orblade and tends to create an eddy current of air to the rear thereof ina forward direction along the under side of the airfoil and to 15 shieldthe lower portion of the rearward blade from impact. I furthermorepreferably extend the curved surface of the rearward vane or blade atthe bottom to the rear so that even at the higher angles of attackimpact resistance is 20 avoided. In modifying the inlet port of thepassageway as just set forth, its essential characteristie shape is notdeparted from and the increase in lift resulting from its turbinecharacter and the decrease in drag due to the projection of its 25discharged airstream are retained.

The eddy current induced'by the change in form of the inlet ports of thepassageways just referred to, greatly decreases the drag of the airfoil. 'I'he eddy current takes the form of a multi- 30 tude of minuterotatingspirals, the rotation being in a counter-clockwise direction.The result of this is to effect a rolling movement of the air along the,under surface of the airfoil which in large part eliminates the skinfriction between 35 that surface and the stream of air passing beneaththe airfoil. With the solid airfoil commonly used commercially, such forexample as' the Clark Y, at low angles of attack the spiral eddiesbeneath the wing are barely detectable 40 and have not been consideredlas functional. In fact any function which might be attributed to them isnegligible. j I have discovered that the very important function aboveset forth is present when the eddies are increased in magnitude andnumber by the improved form of inlet port for the passageways above setforth and this whether or not the passageways be open or closed.

The terms clockwise and counter-clockwise frequently employed herein areto be inter- 50 preted as referring to the direction of motion of theair eddies or mechanical parts to which they are applied when viewedfrom the left side of the airplane.

In furtherance of the said object of decreasing the drag particularly inthe lower angles of attack the present invention incorporates a hingedor pivotally mounted trailing edge section, commonly referred to as aflap, of novel and advantageous design the forward wall of whichcomprises the rear vane or blade of a turbine passageway constructed inaccordance with the present invention. This turbine passageway islocated immediately to the front of the trailing edge section or flapand its opening and closing is controlled by the position of thetrailing edge section or ap. The ap has a normal position very differentfrom that in the prior art. Its turbine passageway is preferably closedand its upper surface instead of continuing the smooth unbroken curve ofthe upper camber of the airfoil extends rearwardly therefrom in a planesubstantially parallel with the longitudinal axis of the airplane so asto be substantially in line with the flight path on straight-awayflight. In this position, therefore, the normal stream of air above theairfoil continues unbroken over the trailing edge section or flapwithout the formation of trailing edge vortices, and to this extent thedrag is reduced. Both in normal position and in its downward position,however, the flap by reason of its said peculiar and novel form, tendsto prevent trailing edge vortices above its rear edge. Furthermore inits downward position the flap cooperates with the downwardly extendingforward vanes or blades of the passageways in directing pressure airtherethrough to increase the lift and decrease the drag of the airfoil.

A further object of the invention in the preferred form thereof indecreasing drag with an airfoil provided with turbine passageways is todesign the leading edge of the airfoil in such a way that the top of thenosepiece presents a smooth unbroken surface from its forward marginbackward to the maximum ordinate of the top camber curve, to which endthe forward passageway of the airfoil should have its outlet port to therear of said maximum ordinate. Preferably the inlet port of the forwardor nosepiece passageway on the lower surface of the airfoil should be tothe front of said maximum ordinate.

A further object of the invention is to provide for automatic openingand closing of the turbinev passageways characterized as above and moreparticularly those in advance of the flap passageway. In attaining thisobject I preferably though not necessarily combine means for manualopening and closing of the passageways with the means providing forautomatic operation thereof.

A further object of the invention where automatic opening and closing ofthe passageways are provided for is to effect said automatic opening andclosing at predetermined angles of attack.

Further objects of the invention will be apparent as this specificationproceeds.

I have chosen as a means for illustrating my invention a high wingmonoplane equipped with the usual landing gear for taking off andlanding on the ground, and for simplicity of showing have illustratedonly two passageways in each airfoil, the nosepiece passageway at thefront and the ap passageway at the rear. It should be understood,however, that this is purely for convenience of illustration and is notto be considered in any sense as limitative on the scope of thisinvention either in respect to the type of plane shown or to the numberof passageways embodied in the airfoil. The drawings are in large partschematic. In these drawings,-

Figure 1 is a plan of the airplane selected for illustration with theairfoils embodying one form of this invention;

Fig. 2 is a crossl section of the right hand airfoil of Fig. 1, on. anenlarged scale, on the dot and dash line 2--3 of Fig. 1 with thetrailing edge section or flap in normal position, the wing tip andaileron being omitted for clearness of showing:

Fig. 3 is a cross section of the right hand airfoil of Fig. l, on anenlarged scale, likewise on the dot and dash line 2--3 except that thetrailing edge section or flap is in its downward position, the wing tipand aileron being omitted for clearness of showing:

Fig. 4 is an end view of the right hand airfoil of Fig. 1, on anenlarged scale:

Fig. 5 is a perspective broken away of the right hand airfoil of Fig. 1,on an enlarged scale, illustrating the mounting and operating structurefor the nosepiece and trailing edge sections:

Figs. 6 to 9 inclusive, are diagrammatic representations of airfoilsillustrating the airflow about the airfoils, Figs. 6 and 7 showing anairfoil of substantially the same dimensions as that of Fig. 1 except ofthe solid type, and Figs. 8 and 9 showing the airfoil of Fig. 1. Figs. 6and 8 represent the airflow about the respective airfoils at low anglesof attack and Figs. 7 and 9 at higher angles of attack. The airflowlines of Figs. 8 and 9 when compared respectively with those of Figs. 6and 7, indicate in part the functional effect of the invention hereinset forth.

'I'he fuselage I0 of the airplane illustrated has mounted thereon at thetop in usual well known manner an airfoil Il at the left side and anairfoil I2 at the right side. Aside from the reversal of the wing partsnecessitated by the fact that one wing is to the left and the other tothe right of the fuselage, the wings are'of id entical construction andthe description of that construction, therefore, can be limited to onewing, the right wing I2, as shown in Fig. 1, being selected for thispurpose.

The airfoil I2, as set forth in the preamble hereof, is for convenienceof illustration shown as provided only with a forward or nosepiecepassageway and a rearward or trailing edge or flap passageway, it beingunderstood that additional passageways such as illustrated in my said U.S. Letters Patent No. 2,077,070, may, if desired, be provided. With onlythe nosepiece and trailing edge of flap passageways herein shown, theairfoil ls formed with a main supporting section I5, a leading edgesection or nosepiece I6, a trailing edge section or nap I'I, an aileronI8, and a wing tip I9.

The main supporting section I5 is hollow and incloses the internalbracing structure of the wing. This bracing structure is preferablybuilt along conventional lines and is schematically illustrated hereinas comprising a forward spar 23 and a rearward spar 24 connected withthe usual cross bracing 25 and with chordwise panels 26, technicallyreferred to in the art as ribs, provided at suitable intervals, which(except for the spars 23, 24) extend in cross section throughout theinner hollow of the main supporting section of the wing, one ofsaid'panels being at each end of that section.

The leading edge section or nosepiece I6, like the main supportingsection I 5, is hollow and incloses its own supporting structure whichas illustrated comprises a relatively large metallic tubular spar 30,the outer shell of the nosepiece being carried on that spar by chordwisepanels 3| J Pmounted at suitable intervals in 'the nosepiece andextending in cross section (except for the spar 30) throughout the innerhollow of the nosepiece, one of said panels being at each end of thenosepiece.

The trailing edge sction or flap I 1 likewise like the main supportingsection I5 is hollow and incloses its own supporting structure which as1illustrated comprises a metallic tubular spar 34, the outer shell ofthe trailing edge section or flap being carried on that spar bychordwise panels 35 mounted at suitable intervals in the trailing edgesection or flap and extending in cross section` (except for the spar 34)throughout the inner hollow of the trailing edge section or ap, one ofsaid panels being at each end of the trailing edge section or flap.

'I'he aileron I8 is, except as to its preferred upper and lower camber,later to be referred to, of

conventional structure and mounting, and provided with the usual meansfor manual control, not shown. It is preferably rigged, however, so

that in normal position it lies in line -with the ap I1, when the flapis in'normal position as stated in the preamblehereof and later to bemore fully described. As will be readily understood, the front wall ofthe aileron I8 is semi-circular in cross section and is mounted forrotation about the center in the aileron of thecircle from which thefront wall is struck. The front wall with only sufficient clearanceabuts against the rear wall of the main supporting section I5 and of thewing tip I9, which rear wall is in cross section of cooperatingsemi-circular curvature, being the sector of a circle struck from thesame center as is the forward curvature of the aileron I8 but with aslightly longer radius to afford the necessary clearance. As this is allof conventional construction no detailed showing of the same is made. Itwill be apparent from the foregoing that there is preferably no turbinepassageway provided betwee'n the aileron I8 and the main supportingsection I5 and the wing tip I9.

'I'he wing tip I 8 -may be of any conventional design and structure suchas illustrated, and as such is carried by the strutted framework of themain supporting section I5 in a well known manner, no detailed showingof the same being herein made. It should be understood, however, thatthis invention is not to be considered as limited to the employment ofconventional wing tips, and that wing tips of improved design andstructure may of course be employed without departure therefrom. Asanexample of suchimproved Wing tips reference may be had to my copendingapplication Ser. No. 116,246, filed December '7, 1936, issued as U.v S.Letters Patent No. 2,125,738.

The leading edge section or nosepiece I6 and the trailing -edge sectionor flap I1 are each rotatably supported in bearings or journals carriedrespectively on the forward spar 23 and the rearward spar 24 in likemanner as in the present practice respecting the mounting of flaps andailerons, a suitable number of said bearings or journals being provided.One of said bearings or journals 40 is illustrated in the broken awaypor'- tion of Fig. 5. Reference being had to that bearing or journal, itwill be apparent that it projects through the rear wall of the mainsupporting section I5 and into the interior of the trailing edge sectionor flap I1 where it carries the tubular spar 34 rotatably mountedtherein.

'I'he structural characteristics of the airfoil as above set forthassure great strength of the air-J vidual parts. The rectangularframework of the main supporting section at the root of the wing isfurthermore suitable for firm attachment to the structural framework ofthe fuselage, such that no exterior bracing is required. It will beunderstood that the forward and rear spars (23, 24) of the mainsupporting section of the airfoil may if desired be extended at the rootof the wing into suitable fuselage framework for cantilever support ofthe airfoil.

The exterior conformation of the airfoil selected for illustration is,except for the wing tip, best illustrated in Figs. 2 and 3, wherein thecharacteristic features of the present invention are likewise moreparticularly shown.

The top camber of the airfoil is, as will well be understood, to bedetermined from the standpoint of eilciency dependent on the characterand type of airfoil selected as best suited for the purpose to which theairplane is primarily designed. 'Ihe top camber shown, therefore, inFigs. 2 and 3 should be understood as merely illustrative and aconvenient showing for describing the invention. I do prefer, however,although it is not essential, that the top surfaceV of the trailing edgesection or flap I1 be substantially fiat throughout, and as an aid inattaining high angles /of attack that the nosepiece I6 have a pronouncedhigh camber and be ratcher blunt as indicated. 'Ihe lower surface of thenosepiece, as shown more particularly in Figs. 2 and 3, should be formedwith a convex camber curve of sufcient chord to give to the impactairstream a substantially definite flow line for the low angles ofattack heretofore referred to, such for example as is illustrated inFigs. 8v and 9 later to be more fully described. The contour of thelower surface of the remainder of the wing will be apparent as thisdescription proceeds.

The rear wall of the leading edge section or nosepiece terminates in acurved vane or blade 44 of such curvature as to form the forward vane orblade of a turbine passageway as set forth in the preamble hereof. Atthe bottom of said vane or blade 44 the curvature extends slightly tothe rear as at the reference numeral 45, but this preferably withoutbreaking the smooth contour of the vane or blade, At the bottom of therearwardly extending curved vane portion 45, the vane or blade unites ina rounded edge with the lower curved surface of the leading edge sectionor nosepiece I6 which should be given the desired camber, as aboveindicated, in manner well understood by those'skilled in the art.

I'he forward wall ofthe main supporting section of the airfoil I5terminates in a vane or blade 48 of such curvature as to form therearward vane or blade of a turbine passageway as set forth in thepreamble hereof, the vanes or blades 44 and 48 cooperating to form theturbine passageway 49. At the bottom of such vane or blade 48, thecurvature extends slightly to the rear as at the reference numeral 50,but this preferably without breaking the smooth contour of the vane orblade. tending curved portion 50, the vane or blade merges into thelower surface of the main supporting section I5 which may be given adesired camber, as above indicated, in manner well understood by thoseskilled in the art. As illustrated, the bottom surface of the mainsupporting section VI5 is substantially at without any curvaturewhatsoever other than that at the lower portions of its forward and rearwalls.

The rearwardly curved portion 45 of the vane At the bottom of therearwardly exor blade 44 extends downwardly below the rear- Wardlycurvedportion 50 of the vane or blade 48. 'Ihis is graphically illustrated byreference to the dot and dash line B-Con Fig. 2 drawn to continue thelower camber'curve of the nosepiece to the trailing edge of the flap inconventional position (indicated in dotted lines) as the theoreticalbottom curve for a wing of semi-symmetrical or convex bottom camber. Asa result of this and of the respective curvatures employed 'the eddycurrent beneath the main supporting section of the airfoilhereinabovereferred to and later to be more particularly described, is set up onthe flight of the airplane, and impact resistance on the vane or blade48 at the bottom thereof is prevented.

The mean cross-sectional line of the passageway 49, indicated by the dotand dash line M-M in Fig. 3, comprises the segment of a spiral in likemanner as in the preferred form of passageway specically chosen forvillustration in my said U. S. Letters Patent No, 2,077,070. As setforth in said Letters Patent the said spiral of which the said meancross-sectional line is a segment is by preference logarithmic, thoughis not essentially so, reference being had to said U. S. Letters Patentfor a full discussion of this particular feature of my turbinepassageway. The rear wall of the main supporting section l5 terminatesin a curved vane. or blade 54 of such, curvature as to form the forwardvane or blade of a turbine passageway as set forth in the preamblehereof. At the bottom of said vane or blade 54 the curvature extendsslightly to the rear as at the reference numeral 55, but this preferablywithout breaking the smooth contour of the vane or blade. At the bottomof the rearwardly extending curved portion 55, the vane or blade mergesinto the lower surface of the main supporting section I5. y

The forward wall of the trailing edge section or flap terminates in avane or blade 58 of such curvature as to form -the rearward vane orblade of a turbine passageway, as set forth in the preamble hereof, thevaries or blades 54 and 58 cooperating to form the turbine passageway59. At the bottom of said vane or blade 58 the curvature extendsslightly to the rear as at the reference numeral 6I), but thispreferably without breaking the smooth contour of the vane or blade. thebottom of the rearwardly extending `curved portion 60, the vane or blademerges into the lower surface of the trailing edge section or fiap I1and. forms a continuation of itscamber. The curved portion 55 of thevaneor blade 54 extends downwardly below the rearwardly curved portion Bof the vane or blade 58. As a result of this and of the respective.curvatures -employed an eddy current as hereinabove referred to andlater to be more particularly described is set up at the rear of thecurved portion 55 of the vane or blade 54 on the flight of the airplanewith the trailing edge section or flapin normal position, and impactresistance on-the vane or blade 58 at the bottom thereof is prevented,the latter being true in both normal and downward positions of thetrailing edge section or flap I1.

I'he mean cross-sectional lineof the passageway 59, indicated by the dotand dash line N-N in Fig. 3 comprises the segment vof a spiral in likemanner as hereinabove discussed respecting the mean cross-sectional lineM--M of the pasis of novel and advantageous camber. The carnber of thelower surface 65 of the flap is in cross section a long sweeping curveslightly concave in form from the bottom up. This concave under surfacemerges in front (as above stated) with the rearwardly curved portion 60ofthe vane or blade 58 at which junction the concave portlon of thecamber starts, and it terminates in a long slender point at the rearwhere it joins the upper at surface of the trailing edge section in asubstantial lineal but rounded margin which comprises 4the trailing edgeof the trailing edge section or flap.

i It is preferred that the aileron I8 conform in cross-sectional contourwith the trailing edge section or flap I'l except as to the forward wallthereof, heretofore described as semi-circular. This contour of theaileron of the airfoil chosen for illustration may be observed in theend view thereof shown in Fig. 4.

With the conventional form of wing tip employed as herein illustrated itis preferred that its upper camber where it joins the main supportingsection I5 of the wing and the leading edge section or nosepiece I6thereof, conform with the upper camber of these two members with theforward passageway 49 closed. It is preferred that the lower camber atits junction with the said main supporting section I5 and the leadingedge section or nosepiece I6 not be cut away to the rear of thenosepiece section as in the case of the main supporting section, butthat its camber follow the bottom camber of the leading edge section ornosepiece I6 (in closed position of the slot 49) and continue as at thereference numeral 68 with but slight, if any curvature to its junctionwith the semi-circular rear wall in front of the aileron heretoforedescribed. Such upper and lower camber of the wing tip I9 is graphicallyillustrated in the end view showing of the wing tip in Fig. 4, whereinthe cross-sectional outline of the passageway 49 and of the lower camberof the main supporting section I5 are illustrated in dotted lines.

In view of the identical construction of the right wing I2 and the left.wing II, except for such reversal of parts as is necessitated by thefact that the two wings are on opposite sides of the fuselage, the leftwing II of the airplane is not illustrated in the same detail as theright wing, the left wing I I being only specifically illustrated inFig. 1. To the left wing II in Fig. 1 I have appended to the parts thereillustrated the same reference numerals as heretofore employed on thecorresponding parts of the right wing I2, except that to these referencenumerals I have added a prime (')-this to add to clarity in applying theforegoing description of the right wing I2 to the left wing I I.

Both the forward or nosepiece passageways and the rearward or flappassageways on the right and left Wings, as herein illustrated, aresusceptible of being opened and closed at the top thereof and means areprovided for controlling the extent to which the said passageways may beopened from a substantially complete closure thereof to a maximumopening in which substantially no air can flow through the passagewaysfrom bottom to top in a straight line. I prefer that the opening andclosing of the forward or nosepiece passageways in both of the wings besubstantially simultaneous and the degree of opening of the twonosepiece passageways be uniform. In like manner I prefer that theopening and closing of the rearward or flap passageways be substantiailysimultaneous and the degree of opening of the two flap passageways beuniform. The opening and closing of the nosepiece passageways need notof necessity,vhowever, be correlated in time and degree with the flappassageways, although as it will later appear in the ordinary operationof the invention, the pilot will in many instances so correlate theopening and closing and the degree of opening of the forward and rearpassageways.

The forward or nosepiece passageways have means provided for automaticopening of the same which may be adjusted toa predetermined positiveangle of attack and for automatically effecting closure of thepassageways lat lesser angles of attack. Both forward and rearpassageways have means for manually opening and closing the same at thewill of the operator, the parts being so adjusted and arranged as to theforward passageways that the automatic opening and closing of the sameis under the control of theoperator should the operator desire toforestall or prevent automatic operation.

To secure a substantially simultaneous opening and closing of theforward or nosepiece passageways and a uniform degree of opening thereofand to place said operation under the control of the pilot, I preferthat the operating mechanism of the two forward or nosepiece passagewaysbe interconnected and under a single controlling device. As illustrated,I have shown a tubular shaft 15, suitably mounted respecting theframework of the fuselage which is in line with the tubular supportingspars 30, 30 of the leading edge sections or nosepieces IB, I6respectively, which shaft is firmly attached to the said leading edgesections or nosepieces at their respective roots, the attachmentpreferably being such that the torsional strain of the shaft 15 inrotating the same is transmitted to the said tubular spars 30, 30'. Saidconnection is schematically illustrated respecting the right wing I2 inFig. 5, wherein an annular flange 16 surrounding the shaft 15 andsecurely fastened to the right end thereof is screwed or bolted throughthe chordwise panel 3|, to a similar flange 11, surrounding the tubularspar 30 and securely fastened to the root end thereof. It will beunderstood by those skilled in the art that if for structural reasons orotherwise the two tubular spars 30 and 30', are not in alignment, as forexample in the event that the two wings are mounted at a positive ornegative dihedral angle or are mounted with an angle of sweepback,universal joints (not shown) may be supplied in the shaft 15 to providefor such lack of alignment without loss of synchronism in the openingand closing of the forward or nosepiece passageways.

On the shaft 15 is mounted a crank arm 80, keyed thereto or-otherwiseattached so as to prevent relative motion between the shaft and thecrank arm. From the outer end of the crank arm 80 there depends a link8| pivotally attached thereto at the top and at the bottom pivotallyattached to the operating-'arm 82 of a bell crank 83 which is pivotallymounted at its angle to suitable framework in the fuselage and has itsoperated arm 84 at the outer endA thereof pivotally connected with alink 85, the other end of which link 85 is pivotally connected to thebottom of an operating lever 86.

The operating lever 86 is journaled on a suitably supported shaft 81 ata suitable distance from the Apivotal connection of its bottom with thelink 85 just referred to. The operating lever has a manually operatedspring pressed pawl 88 which cooperates with a ratchet 89 in maintainingthe lever 86 and through its train of apparatus just described, theleading edge sections or nosepieces I 6, IB in the position to which'they are adjusted by the pilot through the said operating lever 86. Theoperating mechanism of the pawl 88, however, embraces a stud 90 whichmay manually be moved into and out of locking engagement with arestraining shoulder 9| on the-operating lever 86 and by which when inengagement therewith the pawl 88 is raised against the action of itsspring out of contact with the ratchet 89 and maintained in suchposition until the stud 90 is released by the operator. The mechanicaldetails of said pawl and ratchet construction and operation are so wellknown to those skilled in the art as to render unnecessary a detailedshowing and description thereof.

A two way stop 92 is suitably attached to the fuselage framework forcooperation with the Y crank arm 82 and it is so adjusted in relationthereto that the counter-clockwise rotation of the leading edge sectionsor nosepieces on opening the forward passageways is arrested when themaximum opening heretofore described is attained, and the clockwiserotation of the leading edge sections or nosepieces arrested whenthe-said passageways are closed. l

An adjustable spring 93 is provided in the train of operating mechanismfor opening and closing the forward passageways heretofore described,here shown as attached between the fuselage framework and the lower endof the link 8|. By properly adjusting the tension of this spring thetension on'the leading edge sections or nosepieces I6, I6 tending tomaintain the same in closing position for the forward passageways may be regulated in such way that the angle of attack at which the forwardpassageways are automatically opened may be predetermined.

The mechanism herein illustrated as provided for nianually opening andclosing the rearward or flap passageways 59, 59 is substantiallyidentical with that heretofore described for opening and closing theforward or nosepiece passageway 49, 49 and a detailed description of itsconstruction and operation is thereof not necessary. It embraces atubular shaft 95, provided with universal joints (not shown) wherenecessary, for interconnecting the trailing edge sections or aps I1,l1', flanges 96 and 91 being preferably employed in like manner as .arethe flanges 16 and 11; a crank arm |00 rigidly mounted on the shaft 95,and a link |0| pivotally attached to the outer end thereof and to theouter end of the operating arm |02 of a pivotally mounted bell crank |03the operated arm |04 of which is connected by a link |05 to the lowerend of an operating lever |06; said operating lever |06 being suitablyjournaled on the shaft 81 and carrying a manually operated springpressed pawl |08 normally maintained in operative contact with asuitably mounted ratchet |09.

As the trailing edge sections or flaps I1, I1 are not herein illustratedas automatically operable, parts corresponding with the stud 90 and itsrestraining shoulder 9| and the yadjustable spring 93 of the train ofoperating mechanism for the leading edge sections or nosepieces |6, I6'are not essential in the train of operating mechanism for the trailingedge sections or flaps I1, I1'. However, a two way stop I2 is provided.

As will be observed by comparing Figs. 2 and 3, the opening and-closingmovement of the trailing fdge stions or flaps is the reverse of that ofthe leading edge sectionsv or nosepieces. Thus, to open the forwardpassageways 49, 49' the leading edge sections or nosepieces are rotatedcounterclockwise and to close the said passageways, clockwise; whilerespecting the passageways 59, 59' to open the same the trailing edgesections or flaps are rotated in a clockwise direction and to close thesaid passageways, in a. counter-clockwise direotion. Furthermore inmoving from normal closed position to open position and back to closedposition, the trailing edge sections or flaps travel through a fargreater arc than do the leading edge sections or nosepieces in theiropening and closing movements.

I have found it convenient to reverse the connections of the links 85and |05 to their respective operating levers 86 and |06, and to employ ashorter leverage in the operating arm 82 of the bell crank 63 than inthe operating arm |02 of the bell crank |03 to compensate for thisdifference in the direction of opening and closing movements of theleading edge sections ornosepieces and the trailing edge sections orflaps and the respective arcs traveled. In this arrangement with theleverage properly proportioned the operating levers 86 and |06 will bothbe pulled to the rear to open their respectively controlled passageways49, 49' and 59, 59' and to the front to close said respectivepassageways. Furthermore, in any aligned position of the operatinglevers 86 and `|06 their respectively controlled passageways will beopened or closed to the same degree of their opening or closure. Thisconvenient indication to the pilot of opening and closure and the degreethereof respecting the two sets ofpassageways is obviously not to beconsidered in any way limitative upon the scope of this invention butrather as a mere incident of the operation of the control mechanismselected for illustration as a means for manually controlling theleading edge sections or nosepieces and trailing edge sections or apsand the passageways governed thereby.

In the preamble hereof, it was stated that in the normal position of thetrailing edge sections or fiaps (Il, |1) their passageways (59, 59') areclosed and their upper surfaces substantially parallel with thelongitudinal axis of the airplane so as to be substantially in line withthe flight path on straight-away flight. While this language will bereadily understood when taken in connection with the airplane herechosen for illustration it may be subject to misinterpretation when theinvention is applied to other types of plane, as for example where theWings are mounted at a dihedral angle. I am not acquainted with anytechnical phraseology by which this normal position of the trailing edgesections or flaps may be specified in relation to the airfoil itself. InFig. 2 I have, however, indicated by the dot and dash line C-C thereference chord line of the wing as conventionally drawn, i. e., astraight line joining the leading and trailing edges with the trailingedge section or flap having its upper surface continuing without breakthe upper camber of the wing. With an airfoil of the upper and lowercamber illustrated, the upper surface of the trailing edge section orflap when in normal position will be parallel with said reference chordline as conventionally drawn. It will appear at once to those skilled inthe art, however, that this might not be true if the leading edge wereraised or lowered 'by change in the forward camber of the leading edgesection or nosepiece. Defining the normal position of the upper surfaceof the trailing edge section or iiap in respect to the reference chordline as conventionally drawn in the claims hereof, should not beconstrued as specifically limited'to that precise language but should onthe contrary be understood in its functional significance and beinterpreted in accordance with its functional disclosure herein.

The position of the trailing edge sections or flaps I1, I1' with maximumopening hereinabove dened of the rearward passageways 59, 59', isconventionally indicated in Fig. 3. It is obviously dependent upon theprecise form of turbine passageway selected and is accordingly subjectto variation as desired. As illustrated, the upper surface of thetrailing edge section or flap in its lower position makes a decidedangle with the upper surface of the main supporting section, and theunder surface of the trailing edge section or flap extends downwardly ata considerable angle to the under surface of the main supportingsection.

From a mechanical aspect the automatic opening and closing of theforward or nosepiece passageways 49, 49 is as follows: 'Ihe stud 90having been engaged with its restraining shoulder 9| and the pawl 88thus withdrawn from operative contact with the ratchet B9 so that theleading edge sections or nosepieces I6, I6' are free to move withintheir limits of movement, it will be observed that the leading edgesections or nosepieces are held in their closing position by theadjustable spring 93 and by the predominating weight of the leading edgesections or nosepieces above and to the rear of their axes of rotation.On the flight of the airplane the forward walls of the leading edgesections or nosepieces are subjected to great impact resistance and theair pressure there localized is correspondingly great. The preponderanceof this air pressure above or below the leading edge is dependent uponthe angle of attack. At the lower angles of attack the balance is above.This gradually diminishes as the angle is increased until atv higherangles the balance is below. As countew balancing the downward airpressure on the upper surface of the leading edge sections `ornosepieces above and to the rear of their axes of rotation there are theupward air pressure on the lower surface of the leading edge sections ornosepieces to the rear of the axes of rotation thereof and the airpressure Within the passageways 49, 49 forward and upward on thenosepiece vanes or blades d5, 45. When on increasing the angle of attackthe forces developed by the air prsure on the lower surface of theleading edge sections or nosepieces and in the passageways 49, 49'exceed the forces tending to maintain the said passageways closed, theleading edge sections or nosepieces will rotate counterclockwise andopen the passageways. The passageways so opened will remain open untilthe forces tending to close them exceed those tending to open. themwhereupon the leading edge sections or nosepieces will rotate clockwiseand automaticallyl close the passageways.

From the foregoing it will be noted that in normal straight-away flightat low angles of attack the forward or nosepiece passageways 49, 49 areautomatically closed, and that from this automatically closed positionthey are automatically opened at a predetermined (by the adjustedtension of the spring 93) higher angle of attack and automaticallyclosed at a lesser angle of attack.

'I'he mechanical opening and closing of the forinduced to decrease thedrag of the airfoil.

ward passageways will readily be understood from the foregoing detaileddescription of the train oi mechanism provided for that purpose. Thestud 90 will of course be manually released from its restrainingshoulder 9| and with the pawl 88 manually withdrawn from the ratchet 89,the pilot may by the controlling lever 86 move the leading edge sectionsor nosepieces I6, I6' te the position desired by him within the range ofmovement hereinabove described and may maintain that position byreleasing the pawl 88 for its spring pressed engagement with the ratchet89.

Likewise it is believed that the manual operation of the trailing edgesections or flaps` I1, I1' and the opening and closing of the rearwardpassageways 59, 59' willl readily be understood from the foregoingdescription of the train of mechanism provided for this purpose. Thepawl |08 having been manually withdrawn from the ratchet |89, the pilotmay be the controlling lever |06 move the trailing edge sections orflaps IT, I1 to the position desired by him within the range of movementhereinabove described and may maintain them in that position byreleasing the pawl |08 for its spring pressed engagement with theratchet |09.

Reference now being had to the airow diagrams Figs. 6 to 9 inclusive, itbeing understood that the following applies to both the right and leftairfoilsy and referring first to Figs'. 6 and 8: It will be observedthat in Fig. 8 with the leading edge section or nosepiece I6 in itsdownward position and the trailing edge section or nap l1 in its normalposition with both passageways 49 and 59 closed, there is formed to therear of the downwardly extending portion of the leading edge section ornosepiece an eddy current which takes the form of a series of spiralrotating eddies comprising as it were a rolling contact between thebottom surface of the main supporting section and the stream of airowing thereunder. This is very substantial as compared with thecorresponding inconsequential eddy current shown in Fig. 6 and ispurposely will furthermore be observed that the airstream beneath thesurface of the airfoil in Fig. 8 does not strike the forward wallof themain supporting section which forms the rearward vane or blade of thepassageway 49, so that no impact resistance is encountered thereby anddrag is correspondingly reduced.

In Fig. 8 rotating spirals of air are formed to the rear'of thedownwardly extended portion of the rear wall of the main supportingsection of the airfoil. 'These reduce drag in providing a rollingcontact between the lower portion of the forward wall of the trailingedge section or ap I1 and the pressure air beneath, and no impactresistance is encountered by said forward wall which forms the 'rearwardvane or blade of the rearwardpassageway 59.

In Fig. 6 it will be seen that the airstream beneath the rear portion ofthe trailing edge section or ap operating in conjunction with that abovethe rear portion of the flap produces trailing edge vortices above theflap`which increase drag. In Fig. 8, however, the trailing edge sectionor flap I1 is raised above the poson of the construction thereof isprojected rear.- wardly more in line with the airstream above thetrailing edge section or iiap and the two streams of air above and belowmingle and tend to prevent the formation of trailing edge vortices.

In comparing the lift and drag features of a conventional airfoil asshown in Fig. 6 with those of an airfoil embodying my invention as shownin Fig. 8, the following is noted: Reference to Figs. 6 and 8 disclosesthat the airstream below the airfoil in Fig. 8 slopes slightly upward tothe rear beneath the trailing edge section or ap, while that in Fig. 6does not have this upward slope. As above seen the direction of theairstram beneath and to the rear of the trailing edge section is one ofthe contributing factors in decreasing the drag. This deflection of theairstream below the airfoil slightly upward beneath the trailing edgesection or flap results Ain some loss of lift as compared with theshowing of Fig. 6. However the decreased drag in Fig. 8 permits increasespeed of the airplane with the same expenditure of motor or propulsionpower and the lift lost by the slightly upward deflection of theairstream beneath the, trailing edge section or flap is more thanrecovered by the increased speed. Nor does this increase of permissiblespeed increase the drag to the same extent las it increases the lift..The air pressure forces acting on an airfoil increase approximately asthe square of the velocity. Under all flying conditions with theairplane in flight the total lift is always more than the total drag.Thus the gain in lift due to the higher velocity alone is alwaysgreater`than the gain in drag resulting from the saidhigher velocity.

For straight-away iiight within the lower angles of attack it isrecommended that the -trailing edge sections or flaps I1, I1', be keptin normal position as above defined with the rearward passageways 59, 59closed, and that the tension of the adjustable spring 93 be' soregulated that the forward passageways 49, 49 are also closed.

Reference now being had more particularly to Figs. rI and 9: The eddycurrent to the rear of the downwardly projecting rearward wall of theleading edge section or nosepiece with'the forward passageway 49 openand the airfoil at the v cated in Fig. 8. This is due in part to thecooperative action of the downwardly extending portion of the rearwardwall of the leading edge y section or nosepiece I6 and the trailing edgesection or flap Il in its lowered position.l Furthermore as in the caseof Fig. 8, the airstream does not strike the forward wall of the mainsupporting section which forms the vane or blade of the passageway 49. Agreater decrease in drag therefore due to these factors ischaracteristic of the airfoil as. shown in Fig. 9 than as shown in Fig.8. Comparing the showing of Fig. 9 with that of Fig. 7, in this respectit will be observed that in Fig. 7 the eddy current beneath the airfoilis still inconsequential.

In Fig. 9 the eddy formed to the rear of the downwardly projectingportion of the rear wall of the main supporting section characterizingFig. 8 is eliminated vand instead the forward wall of the trailing edgesection or flap Il cooperates with the rear wall of the main supportingsection in directing pressure air upwardly through the rearwardpassageway 59. As a result of this drag is reduced, as will now appearin the discussion of the outlet ports of the two passageways.

In Fig. 9 the decrease in drag due to the opening of the outlet ports ofthe passageways 49 and 59 at the top of the airfoil is very marked. Itwill be apparent that as to the passageway 49 the air projectedtherethrough being entirely to the rear of the maximum ordinate of theupper camber occasions no impact resistance whatsoever to the front ofthat maximum ordinate but on the contrary sweeps along over the uppersurface of the main supporting section and tends to prevent the vorticeswhich are there present in the showing of Fig, 7. The airstreamprojected through the outlet port of the rearward passageway 59 sweepsrearwardly and downwardly along the upper surface of the trailing edgesection or flap and tends to prevent the trailing edge vortices therecharacterizing the structure of Fig. 7 which are so pronounced in thatstructure that with the angle of attack there shown the plane is verynear to the critical angle or burble point. In Fig. 9, as in Fig. 8, theconcave under suraface of the trailing edge section or ap il directs theairstream beneath in line with the airstream above and adds itsiniiuence to the reduction of the trailing edge vortices otherwiseformed. In Fig. 7 on the contrary the airstream beneath the trailingedge section or flap is bent up over the edge thereof and greatlycontributes to the harmful vortices there indicated.

The loss of lift occasioned by the upturned position of the trailingedge section or flap Il in Fig. 8 is no longer present with the trailingedge section or ap turned down in the position of Fig. 9. In thisrespect, therefore, the lift coefficients in Figs. 7 and 9 aresubstantially alike. In Fig. 9, however, there are two factors notpresent in Fig. 7 which increase the lift. The first of these is theadvance in the center of pressure, due to the combined effect of thedownwardly projecting portion of the rear wall of the leading edgesection or nosepiece I6 and the trailing edge section or flap I'I in itslowered position in intensifying the eddy current beneath the mainsupporting section and in directing' pressure air through the passageway49; and the second is the force developed within the turbine passagewaysthemselves heretofore referred to and more specifically fully set forthin my said U. S. Letters Patent No. 2,077,070. These two factors givethe airfoil, as shown in Fig. 9, far

greater lift than has the airfoil as shown in Fig. 7. In addition theairfoil as shown in Fig. 9 has the same potentialities of increased liftover the airfoil as shown in Fig. 7, as above set forth respecting theairfoils of Figs. 8 and 6, due to the greater speeds attainable byreason of the decrease in drag.

It is recommended that both passageways be open and the trailingedge'section or ap be in its lower position for takeoff after attainingsufficient speed on the level, for landing and for rising where anglesof attack are desired above as illustrated in Figs, 7 and 9 are advisoryand not compulsory. The pilot knowing the characteristics andfunctioning of the invention as above set forth and being skilled in theart will use his best judgment in how most eiciently to make use of thesaid characteristics and functioning of this invention in the control ofhis plane in meeting the various conditions of takeoff, landing andflight encountered.

The foregoing detailed description has been given for clearness ofunderstanding and no undue limitation should be deduced therefrom butthe appended claims should be construed as broadly as possible in Viewof the prior art.

I claim:

1. An airfoil for an airplane provided with a plurality of vanes orblades forming one or more substantially spanwise passageways extendingthrough the airfoil from the lower surface to the upper surface thereof,the vanes or blades being formed with cooperatingcurved surfaces andbeing so constructed and arranged that the said passageways have theirinlet ports at the bottom of the airfoil to the front of the outletports at the top of the airfoil with the cross-sections of thepassageways diminishing gradually from the inlet to the outlet thereofand the mean cross-sectional line of the passageways graduallyflattening from inlet to outlet with no appreciable straight linepassage for air through the passageways from inlet to outlet, the curvedsurfaces of the cooperating vanes or blades of each passageway extendingrearwardly at the bottom and the forward vane or blade extendingdownwardly below the lower surface of its cooperating rearward vane orblade, the downwardly extending vane or blade on the flight of theairplane tending to inducean eddy current of air to the rear thereof ina forward direction along the under surface of the airfoil.

2. An airfoil for an airplane provided with a plurality of vanes orblades forming one or more substantially spanwise passageways extendingthrough the airfoil from the lower surface to the upper surface thereof,the vanes or blades being formed with cooperating curved surfaces andbeing so constructed and arranged that the said passageways have theirinlet ports at the bottom of the airfoil to the front of the outletports at the top of the airfoil with the cross-sections of thepassageways diminishing gradually from the inlet to the outlet thereofand the mean crosssectional line of the passageways gradually atteningfrom inlet to outlet, means providing for opening and closingthepassageways at the top, means for controlling the extent to which thesaid passageways may be opened from a substantially complete closurethereof to a maximum opening in which substantially no air can fiowthrough the passageways in a straight line, the forward vane or blade ofeach passageway extending downward below the lower surface of itscooperating rearward vane or blade in closed position of saidpassageways, the downwardly extending vane or blade on the flight of theairplane tending to induce an eddy current of air to the rear thereof ina forward direction along the under surface of the airfoil.

3. An airfoil for an airplane provided with a plurality of vanes orblades forming a substantially spanwise passageway extending through theairfoil from the lower surface to the upper surface thereof, the vanesor blades being formed with cooperating curved surfaces and being soconstructed and arranged that the cross-section of the said passagewaydiminishes gradually from the inlet to the outlet thereof and thel meancrosssectional line of the passageway gradually fiattens from inlet tooutlet with no appreciable straight line passage for air through thepassageway from inlet to outlet, means providing for opening and closingthe passageways at the top, the inlet port of the passageway at thebottom being forward of the maximum ordinate of the top camber curve andthe outlet port of the passageway at the top being rearward of saidmaximum ordinate, the curved surfaces of the coope'rating vanes orblades extending rearwardly at the bottom and the forward vane or bladeextending downwardly below `the lower surface of its cooperatingrearward vane or blade, the downwardly extending vane or blade on theflight of the airplane tending to induce an eddy current of air to therear thereof in a forward direction along the under surface of theairfoil.

4. An airfoil for anairplane provided with a 4plurality of vanes orblades forming one or more substantially spanwise passageways extendingthrough the airfoil from the lower surface 4to the lupper surfacethereof, the vanes or blades being formed with cooperating curvedsurfaces and being sov constructed and arranged that the saidpassageways have their inlet ports at the bottom of the airfoil to thefront of the outlet ports at the top of the airfoil with thecross-sections of the passageways diminishing gradually from the inletto the outlet thereof and the mean crosssectional line of thepassageways gradually flattening from inlet to outlet, means forcontrolling the extent to which the said passageways may be opened froma substantially complete closure thereof to a maximum opening in whichsubstantially no air can flow through the passageways in a straightline, means providing for automatic opening of the passageways at apredetermined positive angle of attack and for automatically effectingclosure thereof at lesser angles of attack, said opening and closing ofthe passageways being at the top thereof, the forward vane or blade ofeach passageway extending downward below the lower surface of itscooperating rearward vane or blade in closed position of saidpassageways, the downwardly extending vane or blade on the flight of theplane tending to induce an eddy current of air to the rear thereof in aforward direction along the under surface of the airfoil.

5. An airfoil for an airplane provided with a plurality of vanes orblades forming a substantially spanwise passageway extending through theairfoil from the lower surface to the upper surface thereof, the vanesor blades being formed with cooperating curved surfaces and .being soconstructed and arranged that the said passageway is of the turbine typeand has its inlet port at the bottom forward of the maximum ordinate o-fthe top camber curve and its outlet port at the top rearward of saidmaximum ordinate, the curved surfaces ofthe cooperating vanes or bladesextending rearwardly at the bottom and the forward vane or bladeextending downwardly below the lower surface of its cooperating rearwardvane or blade, the downwardly extending vane or blade on the flight ofthe airplane tending to induce an eddy current of air to the rearthereof in a forward direction along the under surface of the airfoil,means for controlling therextent to which the said passageway maybeopened from a substantially complete closure thereof to a maximumopening in which substantially no air can ow through the passageway in astraight line, and means providing for automaticl opening of thepassageway at a predetermined positive angle of attack and forautomatically effecting closure thereof at lesser angles of attack.

6. An airfoil for an airplane provided with a plurality of vanes orblades forming a substantiallyspanwise passageway extending through theairfoil from the lower surface to the upper surface thereof, the vanesor blades being formed with cooperating curved surfaces and being soconstructed and arranged that the said passageway is of the turbine typeand has its inlet port at the bottom forward of the maximum ordinate ofthe top camber curve and its outlet port at the top rearward of saidmaximum ordinate, the curved surfaces of the cooperating vanes or bladesextending rearwardly at the bottom and the forward Vane or bladeextending downwardly below the lower surface of its cooperating rearwardvane or blade, the downwardly extending vane or blade on the flight ofthe airplane tending to induce an eddy current of air to the rearthereof in a forward direction along the under surface of the airfoil,means for controlling the extent to which the said passageway may beopened from a substantially complete closure thereof to a maximumopening in which substantially no air can flow through the passageway ina straight line, means providing for automatic opening of the passagewayat a predetermined positive angle of attack and for automaticallyeffecting closure thereof at lesser angles of attack, and meanscorrelated with the last named means for effecting manual opening andclosing of the passageways at the will of the operator.

7. An airfoil for an airplane provided with a nosepiece terminating atthe rear in a wall 'constituting a vane or blade, a second vane or blademounted to the rear thereof, the said vanes or blades forming asubstantially spanwise passageway extending through the airfoil from thelower surface to the upper surface thereof, the said vanes` or bladesbeing formed with cooperating curved surfaces and being so constructedvand arranged that the said passageway has its inlet port at the bottomforward of the maximum ordinate of the top camber curve and its outletport at the top rearward of said maximum ordinate with the cross-sectionof the passageway diminishing gradually from the inlet to the outletthereof and the mean cross-sectional line of the passageway graduallyflattening from inlet to outlet with no appreciable straight linepassage for air through the passageway from inlet to outlet, the curvedsurfaces of the two vanes or blades extending rearwardly at the Ibottoniand the forward vane or blade extending downwardly below the lowersurface of its cooperating rearward vane or blade, the downwardlyextending vane or blade on the flight of the airplane tending to inducean eddy current of air to the rear thereof in a forward direction alongthe under surface of the airfoil.

8. An airfoil for an airplane provided witha nosepiece 'terminating atthe rear in a wall constituting a vane or blade, a second vane or blademounted to the rear thereof, the said vanes or 'blades forming asubstantially spanwisepassageway extending through the airfoil from thelower surface to the upper surface thereof, the said vanes or bladesbeing formed with cooperating curved surfaces and being so constructedand arranged that the said passageway is of the turbine type and has itsinlet port at the bottom forward of the maximum ordinate of the topcamber curve and its outlet port at the top rearward of said maximumordinate, the curved surfaces of the two vanes or blades extendingrearwardly at the bottom and the forward vane or blade extendingdownwardly below the lower surface of its cooperating rearward vane orblade, the downwardly extending vane or blade on the flight of theairplane tending to induce an eddy current of air to the rear thereof ina forward direction along the under surface of the airfoil, means forcontrolling the extent to which the said passageway may be opened from asubstantiaily complete closure thereof to a maximum opening in whichsubstantially no air can flow through the passageway in a straight line,and means providing for automatic opening of the passageway at apredetermined positive angle of attack and for automatically effectingclosure thereof at lesser angles of attack.

9. An airfoil for an airplane provided with a nosepiece terminating atthe rear in a wall constituting a vane or blade, a. second vane or blademounted to the rear thereof, the said vanes or blades forming asubstantially spanwise passageway extending through the airfoil from thelower surface to the upper surface thereof, the said .-vanes or bladesbeing formed with cooperating said maximum ordinate, the curved surfacesof the two vanes or blades extending rearwardly at the bottom and theforward vane or blade extending downwardly below the lower surface ofits cooperating rearward vane or blade, the downwardly extending vane orblade on the flight of the airplane tending to induce an eddy current ofair to the rear thereof in a forward direction along the under surfaceof the airfoil, means for controlling the extent to which the saidpassageway may be opened from a substantially complete closure thereofto a maximum opening in which substantially no air can flow through thepassageway in a straight line, means vproviding for automatic opening ofthe passageway at a predetermined positive angle of attack and forautomatically effecting closure thereof at lesser angles of attack, and`means correlated with the last named means for effecting manual openingand closing of the passageway at the will of the operator. y

10. An airfoil for an airplane comprising a main supporting section anda trailing edge section or flap pivotally attached thereto, the mainsupporting section terminating at the rear in a wall constituting a vaneor blade, the trailing edge section or flap terminating at the front ina wall constituting a vane or blade, the said vanes or blades forming asubstantially spanwise passageway extending through the 'airfoil fromthe lower surface to the upper surface thereof, the vanes or bladesbeing formed with cooperating curved surfaces and being -so constructedand arranged that the said passageway is of the turbine type; the saidforward vane or blade of the said passageway extending downwardly belowthe lower surface of its said cooperating rearward vane or blade inclosed position of the s aid passageway, the curved surface of the saidrearward vane or blade extending rearwardly at the bottom; the saidtrailing edge section or flap having a normal position for straight-awayflight with its upper surface substantially parallel with the referencechord line of the air foil as conventionally drawn, the said passagewaybeing closed at the top in said normal position of the trailing edgesection or flap and gradually opened as the trailing edge section orflap is moved downwardly from its normal position; the said downwardlyextending forward vane or blade of the said passageway on the flight ofthe said airplane with the trailing edge section or flap in normalposition tending to prevent impact resistance on the rearward vane orblade.

11. An airfoil for an airplane comprising a. main supporting section anda trailing edge section or flap pivotally attached thereto, the mainsupporting section terminating at the rear in a wall constituting a vaneor blade, the trailing edge section or flap terminating at the front ina wall constituting a vane or blade, the said vanes or blades forming asubstantially spanwise passageway extending through the airfoil from thelower surface to the upper surface thereof, the vanes or blades beingformed with cooperating curved surfaces and being so lconstructed andarranged that the said passageway is of the turbine type; the saidforward vane or blade of the said passageway extending downwardly belowthe lower surface of its said cooperating rearwardY vane or blade inclosed position of the said passageway, the said curved surface of therearward vane or blade extending rearwardly at the bottom; the uppersurface of the said trailing edge section or flap to the rear of itssaid forward wall being substantially flat and the under surface thereofbeing formed with concave curvature from front to back, the upper andlower surfaces meeting to form the trailing edge at the rear; means forcontrolling the extent to which the said passageway may be opened from asubstantially complete closure thereof to a maximum opening in whichsubstantially'no air can flow through the passageway in a straight line,the said trailing edge section or flap having a, normal position forstraightaway ight with its upper surface substantially parallel with thereference chord line of the airfoil as conventionally drawn; the saidpassageway being closed at the top in said normal position of thetrailing edge section or flap and gradually opened as the trailing edge,section or flap is moved downwardly from its normal position; the saiddownwardly extending forward vane or blade of the said passageway on theflight of the airplane with the trailing edge section or flap in normalposition tending to prevent impact resistance on the said rearward vaneor blade, the concave under surface of the trailing edge section or flapwhen lowered to open the said passageway on the flight of the airplanecooperating with the said downwardly extending forward vane or blade todirect pressure air through the said passageway and increase the liftand decrease thedrag of the airfoil.

12. An airfoil for an airplane comprising a.

nosepiece, a main supporting section, and a flap; the nosepieceterminating at the rear in a wall constituting a vane or blade, 'themain supporting section at the front terminating in a wall constitutinga vane or blade, the said vanes or blades tuting a vane or blade, thetwo last specied vanes or blades forming a substantially spanwisepassageway at the rear of the airfoil extending through the airfoil fromthe lower surface to the upper surface thereof; the first mentioned pairof vanes or blades and the second mentioned pair of vanes or bladesbeing respectively formed' port at the bottom forward of the maximumIordinate of the top camber curve and its outlet port at the top rearwardof said maximum ordinate and having its forward vane or blade extendingdownwardly below the lower surface of its cooperating rearward vane orblade, the downwardly extending vane or blade of the forward passagewayon the flight of the airplane. tending to induce an eddy current of,yair to the rear thereof in a forward direction along the under.

surface of the main supporting section of the airfoil; and means underthe oo ntrol'of the pilot for opening the said passageways at the topwhen the iiap is lowered and for closing the said passageways when theflap is raised.

13. An airfoil for an airplane comprising a nosepiece, a main supportingsection, and a nap having a normal position for straight-away night withits upper surface substantially parallel with the reference chord lineas conventionally drawn; the nosepiece terminating at the rear in a wallconstituting a vane or blade, the main supporting section at the frontterminating in a wall constituting a vane or blade, the said vanes orblades forming a substantially spanwise passageway at the front of theairfoil extending through the airfoil from the lower surface to theupper surface thereof; the main supporting section terminating at therear'in a wall constituting a vane or blade', the ilap terminating atthe f-ront in a wall constituting a vane or blade, the two lastspecified vanes or blades forming a substantially spanwise passageway atthe rear of the airfoil extending through the airfoil from the lowersurface to the upper surface thereof; the first mentioned pair of vanesor blades and the second mentioned pair of vanes or blades beingrespectively formed with cooperating curved surfaces and being soconstructed and arranged that the respective passageways formed anddefined thereby have their inlet ports' at the bottom of the airfoil tothe front of the outlet ports at the top of the airfoil with thecross-sections of the passageways diminishing gradually from the inlettothe outlet thereof and the mean cross-sectional line ofthe'passageways gradually flattening from inlet to outlet with noappreciable 3 straight line passage for air through the passageways from.inlet to outlet; vthe forward passageway having its inlet port at thebottom forward of the maximum ordinate of the top camber curve and itsoutlet port at the top rearward of said maximum ordinate and having itsforward vane or blade extending downwardly below the lower surfaceof itscooperating rearward vane or blade, the downwardly extending vane orblade of the forward passageway on the iiight of the airplane tending toinduce aneddy current of air to the rear thereof in asforward directipnalong the under surface of the main supporting section of the airfoil;the said passageways being closed at the top in said normal position ofthe ap; and means under the control of the pilot for gradually openingthe said passageways as the nap is lowered from its said normal positionand for gradually closing the said passageways as the flap is raisedfrom a lowered position to its said normal position. Y

WILLIAM K. ROSE.

